Method of manufacturing semiconductor device, method of processing substrate, substrate processing apparatus, and recording medium

ABSTRACT

There is included (a) loading a substrate where a conductive metal-element-containing film is exposed on a surface of the substrate into a process chamber under a first temperature; (b) supplying a reducing gas to the substrate while raising a temperature of the substrate to a second temperature higher than the first temperature in the process chamber; (c) forming a first film on the metal-element-containing film, by supplying a first process gas, which does not include an oxidizing gas, to the substrate under the second temperature in the process chamber; and (d) forming a second film on the first film such that the second film is thicker than the first film, by supplying a second process gas, which includes an oxidizing gas, to the substrate under a third temperature higher than the first temperature in the process chamber.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a Bypass Continuation Application of PCTInternational Application No. PCT/JP2019/008550, filed on Mar. 5, 2019,the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a method of manufacturing asemiconductor device, a method of processing a substrate, a substrateprocessing apparatus, and a recording medium.

BACKGROUND

As a process of manufacturing a semiconductor device, a process offorming a low dielectric constant film on a heated substrate bysupplying a process gas including an oxidizing gas to the substrate maybe performed.

SUMMARY

The present disclosure provides some embodiments of a technique capableof suppressing an oxidation of a film formed on a substrate when a baseof the film is a metal-element-containing film, while the film is a lowdielectric constant film.

According to one or more embodiments of the present disclosure, there isprovided a technique that includes: (a) loading a substrate where aconductive metal-element-containing film is exposed on a surface of thesubstrate into a process chamber under a first temperature; (b)supplying a reducing gas to the substrate while raising a temperature ofthe substrate to a second temperature higher than the first temperaturein the process chamber; (c) forming a first film, which contains siliconand at least one selected from the group of nitrogen and carbon and doesnot contain oxygen, on the metal-element-containing film, by supplying afirst process gas, which does not include an oxidizing gas, to thesubstrate under the second temperature in the process chamber; and (d)forming a second film, which contains silicon, oxygen, carbon, andnitrogen, on the first film such that the second film is thicker thanthe first film, by supplying a second process gas, which includes anoxidizing gas, to the substrate under a third temperature higher thanthe first temperature in the process chamber.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration view of a vertical process furnaceof a substrate processing apparatus suitably used in one or moreembodiments of the present disclosure, in which a portion of the processfurnace is shown in a vertical cross section.

FIG. 2 is a schematic configuration view of the vertical process furnaceof the substrate processing apparatus suitably used in the embodimentsof the present disclosure, in which a portion of the process furnace isshown in a cross section taken along line A-A in FIG. 1.

FIG. 3 is a schematic configuration diagram of a controller of thesubstrate processing apparatus suitably used in the embodiments of thepresent disclosure, in which a control system of the controller is shownin a block diagram.

FIG. 4 is a diagram showing a substrate-processing sequence according toone or more embodiments of the present disclosure.

FIG. 5 is a diagram showing a gas-supplying sequence in first filmformation according to one or more embodiments of the presentdisclosure.

FIG. 6 is a diagram showing a gas-supplying sequence in second filmformation according to one or more embodiments of the presentdisclosure.

FIG. 7A is an enlarged cross-sectional view of the surface of a targetwafer having a W film exposed on the surface of the wafer.

FIG. 7B is an enlarged cross-sectional view on the surface of the waferafter a ramp-up+H₂ pre-flow is performed to remove a native oxide layerfrom the surface of the W film.

FIG. 7C is an enlarged cross-sectional view on the surface of the waferafter first film formation is performed to form a SiN film on the Wfilm.

FIG. 7D is an enlarged cross-sectional view on the surface of the waferafter second film formation is performed to form a SiOCN film on the SiNfilm and the SiN film formed in the first film formation is modifiedinto a SiON film.

FIG. 8 is a diagram showing the evaluation results regarding anoxidation-suppressing effect of the W film by performing the first filmformation before the second film formation.

DETAILED DESCRIPTION One or More Embodiments of the Present Disclosure

One or more embodiments of the present disclosure will be now describedmainly with reference to FIGS. 1 to 7D.

(1) Configuration of Substrate Processing Apparatus

As shown in FIG. 1, a process furnace 202 includes a heater 207 as aheating mechanism (a temperature adjustment part). The heater 207 has acylindrical shape and is supported by a support plate so as to bevertically installed. The heater 207 also functions as an activationmechanism (an excitation part) configured to thermally activate (excite)a gas.

A reaction tube 203 is disposed inside the heater 207 to be concentricwith the heater 207. The reaction tube 203 is made of, for example, aheat resistant material such as quartz (SiO₂) or silicon carbide (SiC),and has a cylindrical shape with its upper end closed and its lower endopened. A manifold 209 is disposed to be concentric with the reactiontube 203 under the reaction tube 203. The manifold 209 is made of, forexample, a metal material such as stainless steel (SUS), and has acylindrical shape with both of its upper and lower ends opened. Theupper end portion of the manifold 209 engages with the lower end portionof the reaction tube 203 so as to support the reaction tube 203. AnO-ring 220 a serving as a seal member is installed between the manifold209 and the reaction tube 203. Similar to the heater 207, the reactiontube 203 is vertically installed. A process container (reactioncontainer) mainly includes the reaction tube 203 and the manifold 209. Aprocess chamber 201 is formed in a hollow cylindrical portion of theprocess container. The process chamber 201 is configured to accommodatewafers 200 as substrates. Process to the wafers 200 is performed in theprocess chamber 201.

Nozzles 249 a and 249 b serving as first and second supply parts,respectively, are installed in the process chamber 201 so as topenetrate through a sidewall of the manifold 209. The nozzles 249 a and249 b are also referred to as first and second nozzles, respectively.The nozzles 249 a and 249 b are made of a non-metal material which is aheat resistant material such as quartz or SiC. The nozzles 249 a and 249b are configured as common nozzles to be used for supplying a pluralityof types of gases, respectively.

Gas supply pipes 232 a and 232 b serving as first and second pipes,respectively, are connected to the nozzles 249 a and 249 b,respectively. The gas supply pipes 232 a and 232 b are configured ascommon pipes to be used for supplying a plurality of types of gases,respectively. Mass flow controllers (MFCs) 241 a and 241 b, which areflow rate controllers (flow rate control parts), and valves 243 a and243 b, which are opening/closing valves, are installed in the gas supplypipes 232 a and 232 b, respectively, sequentially from the upstream sideof a gas flow. Gas supply pipes 232 e and 232 g are connected to the gassupply pipe 232 a at the downstream side of the valves 243 a. MFCs 241 eand 241 g and valves 243 e and 243 g are installed in the gas supplypipes 232 e and 232 g, respectively, sequentially from the upstream sideof a gas flow. Gas supply pipes 232 c, 232 d, 232 f, and 232 h areconnected to the gas supply pipe 232 b at the downstream side of thevalves 243 b. MFCs 241 c, 241 d, 241 f, and 241 h and valves 243 c, 243d, 243 f, and 243 h are installed in the gas supply pipes 232 c, 232 d,232 f, and 232 h, respectively, sequentially from the upstream side of agas flow. The gas supply pipes 232 a to 232 h are made of, for example,a metal material such as SUS.

As shown in FIG. 2, each of the nozzles 249 a and 249 b is disposed inan annular space in a plane view between an inner wall of the reactiontube 203 and the wafers 200 so as to extend upward from a lower portionof the inner wall of the reaction tube 203 to an upper portion thereof,that is, along an arrangement direction of the wafers 200. Specifically,each of the nozzles 249 a and 249 b is installed in a regionhorizontally surrounding a wafer arrangement region in which the wafers200 are arranged at a lateral side of the wafer arrangement region,along the wafer arrangement region. Gas supply holes 250 a and 250 b forsupplying a gas are installed on the side surfaces of the nozzles 249 aand 249 b, respectively. Each of the gas supply holes 250 a and 250 b isopened toward the centers of the wafer 200 s in a plane view, whichenables a gas to be supplied toward the wafers 200. A plurality of gassupply holes 250 a and 250 b are installed from the lower portion of thereaction tube 203 to the upper portion thereof.

A precursor gas, for example, a halosilane-based gas containing silicon(Si), which is a main element (predetermined element) constituting afilm, and a halogen element is supplied from the gas supply pipe 232 ainto the process chamber 201 via the MFC 241 a, the valve 243 a, and thenozzle 249 a. The precursor gas refers to a gaseous precursor, forexample, a gas obtained by vaporizing a precursor which remains in aliquid state at room temperature and atmospheric pressure, or aprecursor which remains in a gas state at room temperature andatmospheric pressure. Halosilane is a silane including a halogeno group(halogen group). The halogeno group includes a chloro group, a fluorogroup, a bromo group, an iodine group, and the like. That is, thehalogeno group contains chlorine (Cl), fluorine (F), bromine (Br),iodine (I), and the like. An example of the halosilane-based gas mayinclude a precursor gas containing Si and Cl, that is, achlorosilane-based gas. An example of the chlorosilane-based gas mayinclude a hexachlorodisilane (Si₂Cl₆, abbreviation: HCDS) gas. The HCDSgas acts as a Si source.

A reaction gas, for example, a nitrogen (N)- and hydrogen (H)-containinggas, is supplied from the gas supply pipe 232 b into the process chamber201 via the MFC 241 b, the valve 243 b, and the nozzle 249 b. An exampleof the N- and H-containing gas may include an ammonia (NH₃) gas which isa hydronitrogen-based gas. The NH₃ gas acts as a nitriding gas, that is,a N source.

A reaction gas, for example, a carbon (C)-containing gas, is suppliedfrom the gas supply pipe 232 c into the process chamber 201 via the MFC241 c, the valve 243 c, the gas supply pipe 232 b, and the nozzle 249 b.An example of the C-containing gas may include a propylene (C₃H₆) gaswhich is a hydrocarbon-based gas. The C₃H₆ gas acts as a C source.

A reaction gas, for example, an oxygen (O)-containing gas, is suppliedfrom the gas supply pipe 232 d into the process chamber 201 via the MFC241 d, the valve 243 d, the gas supply pipe 232 b, and the nozzle 249 b.An example of the O-containing gas may include an oxygen (O₂) gas. TheO₂ gas acts as an oxidizing gas, that is, an O source.

A reducing gas, for example, a hydrogen (H₂) gas, which is aH-containing gas, is supplied from the gas supply pipes 232 e and 232 finto the process chamber 201 via the MFCs 241 e and 241 f, the valves243 e and 243 f, the gas supply pipes 232 a and 232 b, and the nozzles249 a and 249 b, respectively.

An inert gas, for example, a nitrogen (N₂) gas, is supplied from the gassupply pipes 232 g and 232 h into the process chamber 201 via the MFCs241 g and 241 h, the valves 243 g and 243 h, the gas supply pipes 232 aand 232 b, and the nozzles 249 a and 249 b, respectively. The N₂ gasacts as a purge gas, a carrier gas, a dilution gas, or the like.

A precursor gas supply system (Si source supply system) mainly includesthe gas supply pipe 232 a, the MFC 241 a, and the valve 243 a. Areaction gas supply system (N source supply system, C source supplysystem, and O source supply system) mainly includes the gas supply pipes232 b to 232 d, the MFCs 241 b to 241 d, and the valves 243 b to 243 d.A reducing gas supply system mainly includes the gas supply pipes 232 eand 232 f, the MFCs 241 e and 241 f, and the valves 243 e and 243 f. Aninert gas supply system mainly includes the gas supply pipes 232 g and232 h, the MFCs 241 g and 241 h, and the valves 243 g and 243 h.

The precursor gas and the reaction gas to be used in first filmformation, which will be described later, are also collectively referredto as a first process gas. Further, the precursor gas supply system andthe reaction gas supply system to be used in the first film formationare also collectively referred to as a first process gas supply system.Further, the precursor gas and the reaction gas to be used in secondfilm formation, which will be described later, are also collectivelyreferred to as a second process gas. Further, the precursor gas supplysystem and the reaction gas supply system to be used in the second filmformation are also collectively referred to as a second process gassupply system.

One or all of the above-described various supply systems may beconfigured as an integrated-type supply system 248 in which the valves243 a to 243 h, the MFCs 241 a to 241 h, and so on are integrated. Theintegrated-type supply system 248 is connected to each of the gas supplypipes 232 a to 232 h. In addition, the integrated-type supply system 248is configured such that operations of supplying various gases into thegas supply pipes 232 a to 232 h (that is, the opening/closing operationof the valves 243 a to 243 h, the flow rate adjustment operation by theMFCs 241 a to 241 h, and the like) are controlled by a controller 121which will be described later. The integrated-type supply system 248 isconfigured as an integral type or detachable type integrated unit, andmay be attached to and detached from the gas supply pipes 232 a to 232 hand the like on an integrated unit basis, so that the maintenance,replacement, extension, etc. of the integrated-type supply system 248can be performed on an integrated unit basis.

An exhaust port 231 a for exhausting an internal atmosphere of theprocess chamber 201 is installed below the sidewall of the reaction tube203. The exhaust port 231 a may be installed from a lower portion of thesidewall of the reaction tube 203 to an upper portion thereof, that is,along the wafer arrangement region. An exhaust pipe 231 is connected tothe exhaust port 231 a. A vacuum exhaust device, for example, a vacuumpump 246, is connected to the exhaust pipe 231 via a pressure sensor245, which is a pressure detector (pressure detecting part) fordetecting the internal pressure of the process chamber 201, and an autopressure controller (APC) valve 244, which is a pressure regulator(pressure adjustment part). The APC valve 244 is configured to performor stop a vacuum exhausting operation in the process chamber 201 byopening/closing the valve while the vacuum pump 246 is actuated, and isalso configured to adjust the internal pressure of the process chamber201 by adjusting an opening degree of the valve based on pressureinformation detected by the pressure sensor 245 while the vacuum pump246 is actuated. An exhaust system mainly includes the exhaust pipe 231,the APC valve 244, and the pressure sensor 245. The exhaust system mayinclude the vacuum pump 246.

A seal cap 219, which serves as a furnace opening cover configured tohermetically seal a lower end opening of the manifold 209, is installedunder the manifold 209. The seal cap 219 is made of, for example, ametal material such as SUS, and is formed in a disc shape. An O-ring 220b, which is a seal member making contact with the lower end portion ofthe manifold 209, is installed on an upper surface of the seal cap 219.A rotation mechanism 267 configured to rotate a boat 217, which will bedescribed later, is installed under the seal cap 219. A rotary shaft 255of the rotation mechanism 267 is connected to the boat 217 via the sealcap 219. The rotation mechanism 267 is configured to rotate the wafers200 by rotating the boat 217. The seal cap 219 is configured to bevertically moved up and down by a boat elevator 115 which is anelevating mechanism installed outside the reaction tube 203. The boatelevator 115 is configured as a transfer system (transfer mechanism)which loads/unloads (transfers) the wafers 200 into/out of the processchamber 201 by moving the seal cap 219 up and down. A shutter 219 s,which serves as a furnace opening cover configured to hermetically seala lower end opening of the manifold 209 in a state where the seal cap219 is lowered and the boat 217 is unloaded from an interior of theprocess chamber 201, is installed under the manifold 209. The shutter219 s is made of, for example, a metal material such as SUS, and isformed in a disc shape. An O-ring 220 c, which is a seal member makingcontact with the lower end portion of the manifold 209, is installed onan upper surface of the shutter 219 s. The opening/closing operation(such as elevation operation, rotation operation, or the like) of theshutter 219 s is controlled by a shutter-opening/closing mechanism 115s.

The boat 217 serving as a substrate support is configured to support aplurality of wafers 200, for example, 25 to 200 wafers, in such a statethat the wafers 200 are arranged in a horizontal posture and in multiplestages along a vertical direction with the centers of the wafers 200aligned with one another. As such, the boat 217 is configured to arrangethe wafers 200 to be spaced apart from each other. The boat 217 is madeof a heat resistant material such as quartz or SiC. Heat-insulatingplates 218 made of a heat resistant material such as quartz or SiC aresupported below the boat 217 in multiple stages.

A temperature sensor 263 serving as a temperature detector is installedin the reaction tube 203. Based on temperature information detected bythe temperature sensor 263, a degree of supplying electric power to theheater 207 is adjusted such that the interior of the process chamber 201has a desired temperature distribution. The temperature sensor 263 isinstalled along the inner wall of the reaction tube 203.

As shown in FIG. 3, a controller 121, which is a control part (controlmeans), is configured as a computer including a central processing unit(CPU) 121 a, a random access memory (RAM) 121 b, a memory 121 c, and anI/O port 121 d. The RAM 121 b, the memory 121 c, and the I/O port 121 dare configured to be capable of exchanging data with the CPU 121 a viaan internal bus 121 e. An input/output device 122 formed of, e.g., atouch panel or the like, is connected to the controller 121.

The memory 121 c is configured by, for example, a flash memory, a harddisk drive (HDD), or the like. A control program for controllingoperations of a substrate processing apparatus, a process recipe inwhich sequences and conditions of substrate processing to be describedlater are written, etc. are readably stored in the memory 121 c. Theprocess recipe functions as a program for causing the controller 121 toexecute each sequence in the substrate processing, which will bedescribed later, to obtain an expected result. Hereinafter, the processrecipe and the control program may be generally and simply referred toas a “program.” Furthermore, the process recipe may be simply referredto as a “recipe.” When the term “program” is used herein, it mayindicate a case of including the recipe only, a case of including thecontrol program only, or a case of including both the recipe and thecontrol program. The RAM 121 b is configured as a memory area (workarea) in which a program or data read by the CPU 121 a is temporarilystored.

The I/O port 121 d is connected to the MFCs 241 a to 241 h, the valves243 a to 243 h, the pressure sensor 245, the APC valve 244, the vacuumpump 246, the temperature sensor 263, the heater 207, the rotationmechanism 267, the boat elevator 115, the shutter-opening/closingmechanism 115 s, and so on.

The CPU 121 a is configured to read and execute the control program fromthe memory 121 c and is also configured to read the recipe from thememory 121 c according to an input of an operation command from theinput/output device 122. The CPU 121 a is configured to control theflow-rate-adjusting operation of various kinds of gases by the MFCs 241a to 241 h, the opening/closing operation of the valves 243 a to 243 h,the opening/closing operation of the APC valve 244, the pressureadjusting operation performed by the APC valve 244 based on the pressuresensor 245, the actuating and stopping operation of the vacuum pump 246,the temperature adjusting operation performed by the heater 207 based onthe temperature sensor 263, the operations of rotating the boat 217 andadjusting the rotation speed of the boat 217 with the rotation mechanism267, the operation of moving the boat 217 up and down by the boatelevator 115, the opening/closing operation of the shutter 219 s by theshutter-opening/closing mechanism 115 s, and so on, according tocontents of the read recipe.

The controller 121 may be configured by installing, on the computer, theaforementioned program stored in an external memory 123. Examples of theexternal memory 123 may include a magnetic disk such as a HDD, anoptical disc such as a CD, a magneto-optical disc such as a MO, asemiconductor memory such as a USB memory, and the like. The memory 121c or the external memory 123 is configured as a non-transitorycomputer-readable recording medium. Hereinafter, the memory 121 c andthe external memory 123 may be generally and simply referred to as a“recording medium.” When the term “recording medium” is used herein, itmay indicate a case of including the memory 121 c only, a case ofincluding the external memory 123 only, or a case of including both thememory 121 c and the external memory 123. Furthermore, the program maybe provided to the computer using communication means such as theInternet or a dedicated line, instead of using the external memory 123.

(2) Substrate-Processing Process

As a process of manufacturing a semiconductor device using theabove-described substrate processing apparatus, a substrate-processingsequence example of removing a native oxide film formed on the surfaceof a conductive metal-element-containing film (hereinafter also simplyreferred to as a metal-containing film) exposed on a wafer 200 as asubstrate and then forming a low dielectric constant film on themetal-containing film while suppressing oxidation of themetal-containing film will be described mainly with reference to FIGS. 4to 7D. In the following descriptions, the operations of the respectiveparts constituting the substrate processing apparatus are controlled bythe controller 121.

The substrate-processing sequence shown in FIG. 4 includes:

-   -   a step of loading a wafer 200 having a tungsten (W) film as a        conductive metal-element-containing film exposed on the surface        of the wafer 200 into a process chamber 201 under a first        temperature (wafer charging and boat loading);    -   a step of supplying a H₂ gas as a reducing gas to the wafer 200        while raising the temperature of the wafer 200 to a second        temperature higher than the first temperature in the process        chamber 201 (ramp-up+H₂ pre-flow);    -   a step of forming a silicon nitride film (SiN film) as a first        film containing Si and at least one selected from the group of N        and C and not containing O on the W film by supplying a HCDS gas        and an NH₃ gas as a first process gas including no oxidizing gas        to the wafer 200 in the process chamber 201 under the second        temperature (first film formation); and    -   a step of forming a silicon oxycarbonitride film (SiOCN film) as        a second film containing Si, O, C, and N, which is thicker than        the SiN film, on the SiN film by supplying a HCDS gas, an O₂        gas, a C₃H₆ gas, and an NH₃ gas as a second process gas        including an oxidizing gas to the wafer 200 in the process        chamber 201 under a third temperature higher than the first        temperature (second film formation).

In the first film formation described above, a cycle which includessupplying the HCDS gas and the NH₃ gas to the wafer 200 is performed apredetermined number of times. In a gas-supplying sequence shown in FIG.5, in the first film formation, a sequence example of performing a cyclem times (where m is an integer of 1 or more and 3 or less), the cycleincluding intermittently and non-simultaneously supplying the HCDS gasand the NH₃ gas to the wafer 200, is shown.

Further, in the second film formation described above, a cycle whichincludes supplying the HCDS gas, the O₂ gas, the C₃H₆ gas, and the NH₃gas to the wafer 200 is performed a predetermined number of times. In agas-supplying sequence shown in FIG. 6, in the second film formation, asequence example of performing a cycle n times (where n is an integer of1 or more), the cycle including intermittently and non-simultaneouslysupplying the HCDS gas, the O₂ gas, the C₃H₆ gas, and the NH₃ gas to thewafer 200, is shown.

In the present disclosure, the gas-supplying sequence of the first filmformation shown in FIG. 5 and the gas-supplying sequence of the secondfilm formation shown in FIG. 6 may be denoted as follows for the sake ofconvenience. The same notation will be used in the following descriptionof other embodiments.

(HCDS→NH₃)×m⇒SiN

(HCDS→C₃H₆→O₂→NH₃)×n⇒SiOCN

When the term “wafer” is used in the present disclosure, it may refer to“a wafer itself” or “a wafer and a laminated body of certain layers orfilms formed on a surface of the wafer.” When the phrase “a surface of awafer” is used in the present disclosure, it may refer to “a surface ofa wafer itself” or “a surface of a certain layer formed on a wafer.”When the expression “a certain layer is formed on a wafer” is used inthe present disclosure, it may mean that “a certain layer is formeddirectly on a surface of a wafer itself” or that “a certain layer isformed on a layer formed on a wafer.” When the term “substrate” is usedin the present disclosure, it may be synonymous with the term “wafer.”

Wafer Charging and Boat Loading

When the boat 217 is charged with a plurality of wafers 200 (wafercharging), the shutter 219 s is moved by the shutter-opening/closingmechanism 115 s and the lower end opening of the manifold 209 is opened(shutter open). Thereafter, as shown in FIG. 1, the boat 217 supportingthe wafers 200 is lifted up by the boat elevator 115 to be loaded intothe process chamber 201 (boat loading). In this state, the seal cap 219seals the lower end of the manifold 209 via the O-ring 220 b.

As a wafer 200, for example, a Si substrate composed of single crystalSi or a substrate having a single crystal Si film formed on the surfaceof the substrate can be used. As shown in FIG. 7A, a W film, which is aconductive metal-element-containing film, is installed in at least aportion of the surface of the wafer 200, and at least a portion of the Wfilm is exposed. A native oxide layer may be formed on the exposedsurface of the W film. In the W film, the ratio (%) of the thickness ofa W layer, which is a portion where the native oxide layer is not formed(not oxidized), and the thickness of a layer having the composition ofWO, (hereinafter also simply referred to as a WO layer), which is aportion where the native oxide layer is formed (oxidized), is, forexample, about 70:30.

When the boat is loaded, in order to suppress the oxidation of the Wfilm, that is, in order to suppress formation of a further WO layer onthe surface of the W film, increase in the thickness of thealready-formed WO layer, etc., it is preferable that the internaltemperature of the process chamber 201 is set to a predetermined firsttemperature, that is, a predetermined temperature within a range of roomtemperature (25 degrees C.) or higher and 200 degrees C. or lower,specifically room temperature or higher and 150 degrees C. or lower.When the internal temperature of the process chamber 201 exceeds 200degrees C., oxidation of the W film may proceed due to the influence ofthe moisture infiltrated into the process chamber 201 when the boat isloaded, the moisture remaining in the process chamber 201 before theboat loading, etc. By setting the internal temperature of the processchamber 201 to 200 degrees C. or lower, it is less susceptible to theinfluence of the moisture infiltrated into the process chamber 201, themoisture remaining in the process chamber 201, etc., which makes itpossible to avoid the oxidation of the W film. By setting the internaltemperature of the process chamber 201 to 150 degrees C. or lower, it ispossible to reliably avoid the oxidation of the W film when the boat isloaded. When the internal temperature of the process chamber 201 islower than the room temperature, a cooling device for cooling theinterior of the process chamber 201 may be required, and the subsequenttemperature-rising time becomes long. As a result, the apparatus costsmay increase and the productivity may decrease. By setting the internaltemperature of the process chamber 201 to the room temperature orhigher, a cooling device for cooling the interior of the process chamber201 may not be required, and the subsequent temperature-rising time canbe shortened. As a result, it is possible to reduce the apparatus costsand improve the productivity.

Further, when the boat is loaded, the valves 243 g and 243 h are openedto allow a N₂ gas to be supplied into the process chamber 201 via thenozzles 249 a and 249 b to purge the interior of the process chamber 201with the N₂ gas. As a result, it is possible to prevent the infiltrationof water and the like into the process chamber 201, promote thedischarge of the residual water and the like from the interior of theprocess chamber 201, etc. The supply flow rate of the N₂ gas (for eachgas supply pipe) is a flow rate within a range of, for example, 0.5 to20 slm.

As an inert gas, in addition to the N₂ gas, a rare gas such as an Argas, a He gas, a Ne gas, a Xe gas, or the like can be used. The sameapplies to each step to be described later.

Ramp-Up+H₂ Pre-Flow

After the boat load is completed, the interior of the process chamber201 is vacuum-exhausted (depressurization-exhausted) by the vacuum pump246 to reach a desired pressure (pressure adjustment). Further, thewafer 200 in the process chamber 201 is heated to rise in temperature bythe heater 207 to reach a desired second temperature higher than thefirst temperature (ramp-up). Further, the rotation mechanism 267 startsto rotate the wafer 200 (rotation). The exhaust of the interior of theprocess chamber 201 and the heating and rotation of the wafer 200 arecontinuously performed at least until the process to the wafer 200 iscompleted.

Then, in parallel with the ramp-up (temperature rise) of the wafer 200,H₂ pre-flow is performed. That is, the valves 243 e and 243 f are openedto allow a H₂ gas to flow into the gas supply pipes 232 e and 232 f Theflow rate of the H₂ gas is adjusted by the MFC 241 e and 241 f, and theH₂ gas is supplied into the process chamber 201 via the nozzles 249 aand 249 b and is exhausted through the exhaust port 231 a. In thisoperation, the H₂ gas is supplied to the wafer 200 (H₂ pre-flow). Atthis time, the valves 243 g and 243 h may be opened to allow a N₂ gas tobe supplied into the process chamber 201 via the nozzles 249 a and 249b.

The process conditions of this step are exemplified as follows.

-   -   H₂ gas supply flow rate (for each gas supply pipe): 1 to 10 slm    -   N₂ gas supply flow rate (for each gas supply pipe): 1 to 10 slm    -   Each gas supply time: 1 to 120 minutes, specifically 1 to 60        minutes    -   Temperature-rising start temperature (first temperature): room        temperature to 200 degrees C., specifically room temperature to        150 degrees C.    -   Temperature-rising target temperature (second temperature): 500        to 800 degrees C., specifically 600 to 700 degrees C.    -   Temperature-rising rate: 1 to 30 degrees C./min, specifically 1        to 20 degrees C./min    -   Processing pressure: 20 to 10,000 Pa, specifically 1,000 to        5,000 Pa    -   The temperature-rising target temperature is also the processing        temperature in the first film formation to be described later.

By supplying the H₂ gas to the wafer 200 while raising the temperatureof the wafer 200 under the aforementioned conditions, that is, byraising the temperature of the wafer 200 under the H₂ gas atmosphere, itis possible to reduce a portion of the W film, which is exposed to thesurface of the wafer 200 to remove the WO layer formed on the surface ofthe W film, as shown in FIG. 7B. The O component contained in the WOlayer constitutes a gaseous substance containing at least O in theprocess of a reaction that occurs when the WO layer is removed, and isdischarged from the process chamber 201. Further, in this step, byraising the temperature of the wafer 200 under the H₂ gas atmosphere, itis possible to prevent the oxidation of the surface of the W film afterthe WO layer is removed.

If the second temperature is lower than 500 degrees C., the effect ofremoving the WO layer by the reduction reaction described above and theeffect of preventing the oxidation of the surface of the W film afterremoving the WO layer may be insufficient. By setting the secondtemperature to a temperature of 500 degrees C. or higher, these effectscan be sufficiently obtained. By setting the second temperature to atemperature of 600 degrees C. or higher, these effects can be surelyobtained.

If the second temperature exceeds 800 degrees C., an excessive vaporphase reaction may occur in the process chamber 201 in the first filmformation to be described later, which may deteriorate the filmthickness uniformity of the film formed on the wafer 200, therebydeteriorating the quality of the film. By setting the second temperatureto 800 degrees C. or lower, this problem can be solved. By setting thesecond temperature to 700 degrees C. or lower, this problem can besurely solved.

As a reducing gas, a deuterium (D₂) gas can be used in addition to theH₂ gas.

After the removal of the WO layer from the surface of the W film iscompleted, the valves 243 e and 243 f are closed to stop the supply ofthe H₂ gas into the process chamber 201. Then, the interior of theprocess chamber 201 is vacuum-exhausted to remove a gas and the likeremaining in the process chamber 201 from the interior of the processchamber 201 (purge). At this time, the valves 243 g and 243 h are openedto allow a N₂ gas to be supplied into the process chamber 201. The N₂gas acts as a purge gas. Even after the removal of the WO layer from thesurface of the W film is completed, the supply of the H₂ gas into theprocess chamber 201 may be continued (maintained) for a predeterminedperiod until the first film formation is started. For example, evenafter the temperature rise of the wafer 200 to the second temperature iscompleted, the supply of the H₂ gas into the process chamber 201 may becontinued for a predetermined period until the first film formation isstarted. In this case, the effect of preventing the oxidation of thesurface of the W film after the WO layer is removed can be continued fora predetermined period until the first film formation is started.

First Film Formation

After that, the next steps C1 and C2 are sequentially executed.

Step C1

In this step, a HCDS gas is supplied to the wafer 200 in the processchamber 201 (HCDS gas supply). Specifically, the valve 243 a is openedto allow the HCDS gas to flow into the gas supply pipe 232 a. The flowrate of the HCDS gas is adjusted by the MFC 241 a, and the HCDS gas issupplied into the process chamber 201 via the nozzle 249 a and isexhausted through the exhaust port 231 a. In this operation, the HCDSgas is supplied to the wafer 200. At this time, the valves 243 g and 243h may be opened to allow a N₂ gas to be supplied into the processchamber 201 via the nozzles 249 a and 249 b.

The process conditions of this step are exemplified as follows

-   -   HCDS gas supply flow rate: 0.01 to 2 slm, specifically 0.1 to 1        slm    -   N₂ gas supply flow rate (for each gas supply pipe): 0 to 10 slm    -   Each gas supply time: 1 to 120 seconds, specifically 1 to 60        seconds    -   Processing temperature (second temperature): 500 degrees C. to        800 degrees C., specifically 600 degrees C. to 700 degrees C.    -   Processing pressure: 1 to 2,666 Pa, specifically 67 to 1,333 Pa

By supplying the HCDS gas to the wafer 200 under the aforementionedconditions, a Si-containing layer containing Cl is formed on theoutermost surface of the wafer 200. The Si-containing layer containingCl is formed by Si deposition or the like on the outermost surface ofthe wafer 200 by physical adsorption of HCDS, chemical adsorption of asubstance (hereinafter, Si_(x)Cl_(y)) obtained when a portion of HCDS isdecomposed, thermal decomposition of HCDS, and the like. TheSi-containing layer containing Cl may be an adsorption layer (physicaladsorption layer or chemical adsorption layer) of HCDS or Si_(x)Cl_(y),or may be a Si deposition layer containing Cl. In the presentdisclosure, the Si-containing layer containing Cl is also simplyreferred to as a Si-containing layer.

After the Si-containing layer is formed, the valve 243 a is closed tostop the supply of the HCDS gas into the process chamber 201. Then, theinterior of the process chamber 201 is vacuum-exhausted to remove a gasand the like remaining in the process chamber 201 from the interior ofthe process chamber 201. At this time, the valves 243 g and 243 h areopened to allow a N₂ gas to flow into the process chamber 201. The N₂gas acts as a purge gas.

As a precursor gas, in addition to the HCDS gas, it may be possible touse, e.g., a chlorosilane-based gas such as a monochlorosilane (SiH₃Cl,abbreviation: MCS) gas, a dichlorosilane (SiH₂Cl₂, abbreviation: DCS)gas, a trichlorosilane (SiHCl₃, abbreviation: TCS) gas, atetrachlorosilane (SiCl₄, abbreviation: STC) gas, or anoctachlorotrisilane (Si₃Cl₈, abbreviation: OCTS) gas. The same appliesto step D1 to be described later.

Step C2

After step C1 is completed, an NH₃ gas is supplied to the wafer 200 inthe process chamber 201, that is, the Si-containing layer formed on thewafer 200 (NH₃ gas supply). Specifically, the valve 243 b is opened toallow the NH₃ gas to flow into the gas supply pipe 232 b. The flow rateof the NH₃ gas is adjusted by the MFC 241 b, and the NH₃ gas is suppliedinto the process chamber 201 via the nozzle 249 b and is exhaustedthrough the exhaust port 231 a. In this operation, the NH₃ gas issupplied to the wafer 200. At this time, the valves 243 g and 243 h maybe opened to allow a N₂ gas to be supplied into the process chamber 201via the nozzles 249 a and 249 b.

The process conditions of this step are exemplified as follows.

-   -   NH₃ gas supply flow rate: 0.1 to 10 slm    -   NH₃ gas supply time: 1 to 120 seconds, specifically 1 to 60        seconds    -   Processing pressure: 1 to 4,000 Pa, specifically 1 to 3,000 Pa    -   Other process conditions are the same as the process conditions        in step C1.

By supplying the NH₃ gas to the wafer 200 under the aforementionedconditions, at least a portion of the Si-containing layer formed on thewafer 200 is nitrided (modified). By modifying the Si-containing layer,a layer containing Si and N, that is, a silicon nitride layer (SiNlayer), is formed on the wafer 200. When forming the SiN layer,impurities such as Cl contained in the Si-containing layer constitute agaseous substance containing at least Cl in the process of modifying theSi-containing layer with the NH₃ gas and are discharged from theinterior of the process chamber 201. As a result, the SiN layer becomesa layer having fewer impurities such as Cl than the Si-containing layerformed in step C1.

After the SiN layer is formed, the valve 243 b is closed to stop thesupply of the NH₃ gas into the process chamber 201. Then, a gas and thelike remaining in the process chamber 201 are removed from the processchamber 201 according to the same processing procedure as in the purgein step C1 (purge).

As a reaction gas (N- and H-containing gas), in addition to the NH₃ gas,it may be possible to use, e.g., a hydrogen nitride-based gas such as adiazene (N₂H₂) gas, a hydrazine (N₂H₄) gas, or a N₃H₈ gas. The sameapplies to step D4 to be described later.

Performing Predetermined Number of Times

By performing a cycle a predetermined number of times (m times, where mis an integer of 1 or more and 3 or less), the cycle includingnon-simultaneously, that is, without synchronization, performing theabove-described steps 1 and 2, as shown in FIG. 7C, it is possible toform a SiN film having a predetermined composition and a predeterminedfilm thickness on the wafer 200, that is, the W film from which the WOlayer is removed by the temperature rise of the wafer 200 under the H₂gas atmosphere.

The thickness of the SiN film is, for example, 0.16 nm or more and 1 nmor less, specifically 0.16 nm or more and 0.48 nm or less, and morespecifically 0.16 nm or more and 0.32 nm or less.

If the thickness of the SiN film is less than 0.16 nm, theoxidation-blocking effect to be described later becomes insufficient, sothat a portion of the W film may be oxidized in the second filmformation to be described later. By setting the thickness of the SiNfilm to 0.16 nm or more, the oxidation-blocking effect can besufficiently obtained, which makes it possible to avoid the oxidation ofthe W film in the second film formation to be described later.

If the thickness of the SiN film exceeds 1 nm, the total dielectricconstant of a laminated film to be described later may increase. Bysetting the thickness of the SiN film to 1 nm or less, it is possible tosuppress the increase in the total dielectric constant of the laminatedfilm to be described later. By setting the thickness of the SiN film to0.48 nm or less, this effect can be surely obtained, and by setting thethickness of the SiN film to 0.32 nm or less, this effect can be moresurely obtained.

The above-mentioned cycle may be repeated multiple times. That is, thethickness of the SiN layer formed when the above-mentioned cycle isperformed once may be set to be smaller than a desired film thickness,and the above-mentioned cycle may be repeated multiple times until thefilm thickness of a SiN film formed by laminating SiN layers reaches thedesired film thickness. By setting the number of times of performing theabove-mentioned cycle to a predetermined number of times of 1 or moreand 3 or less, it is possible to set the thickness of the SiN filmwithin the above-mentioned range.

Second Film Formation

After that, the next steps D1 to D4 are sequentially executed.

Step D1

In this step, a HCDS gas is supplied to the wafer 200 in the processchamber 201 according to the same processing procedure as the processingprocedure in the above-described step C1 (HCDS gas supply).

The process conditions of this step are exemplified as follows.

-   -   HCDS gas supply flow rate: 0.01 to 2 slm, specifically 0.1 to 1        slm    -   N₂ gas supply flow rate (for each gas supply pipe): 0 to 10 slm    -   Each gas supply time: 1 to 120 seconds, specifically 1 to 60        seconds    -   Processing temperature (third temperature): 250 degrees C. to        800 degrees C., specifically 400 degrees C. to 700 degrees C.    -   Processing pressure: 1 to 2,666 Pa, specifically 67 to 1,333 Pa    -   The third temperature may be a temperature higher than the        above-mentioned first temperature. Further, the third        temperature may be the same as the above-mentioned second        temperature.

By supplying the HCDS gas to the wafer 200 under the aforementionedconditions, a Si-containing layer is formed on the wafer 200, that is,on the SiN film formed on the wafer 200.

After the Si-containing layer is formed, the supply of the HCDS gas intothe process chamber 201 is stopped, and a gas and the like remaining inthe process chamber 201 are removed from the process chamber 201according to the same processing procedure as in the purge in step C1(purge).

Step D2

After step D1 is completed, a C₃H₆ gas is supplied to the wafer 200 inthe process chamber 201, that is, the Si-containing layer formed on theSiN film on the wafer 200 (C₃H₆ gas supply). Specifically, the valve 243c is opened to allow the C₃H₆ gas to flow into the gas supply pipe 232c. The flow rate of the C₃H₆ gas is adjusted by the MFC 241 c, and theC₃H₆ gas is supplied into the process chamber 201 via the gas supplypipe 232 b and the nozzle 249 b and is exhausted through the exhaustport 231 a. In this operation, the C₃H₆ gas is supplied to the wafer200. At this time, the valves 243 g and 243 h may be opened to allow aN₂ gas to be supplied into the process chamber 201 via the nozzles 249 aand 249 b.

The process conditions of this step are exemplified as follows.

-   -   C₃H₆ gas supply flow rate: 0.1 to 10 slm    -   C₃H₆ gas supply time: 1 to 120 seconds, specifically 1 to 60        seconds    -   Processing pressure: 1 to 4,000 Pa, specifically 1 to 3,000 Pa    -   Other process conditions are the same as the process conditions        in step D1.

By supplying the C₃H₆ gas to the wafer 200 under the aforementionedconditions, a C-containing layer is formed on the Si-containing layer.As a result, a layer containing Si and C formed by laminating theC-containing layer on the Si-containing layer is formed on the wafer200, that is, on the SiN film on the wafer 200.

After the layer containing Si and C is formed, the valve 243 c is closedto stop the supply of the C₃H₆ gas into the process chamber 201. Then, agas and the like remaining in the process chamber 201 are removed fromthe process chamber 201 according to the same processing procedure as inthe purge in step C1 (purge).

As a reaction gas (C-containing gas), in addition to the C₃H₆ gas, itmay be possible to use, e.g., a hydrocarbon-based gas such as anacetylene (C₂H₂) gas or an ethylene (C₂H₄) gas.

Step D3

After step D2 is completed, an O₂ gas is supplied to the wafer 200 inthe process chamber 201, that is, the layer containing Si and C formedon the SiN film on the wafer 200 (O₂ gas supply). Specifically, thevalve 243 d is opened to allow the O₂ gas to flow into the gas supplypipe 232 d. The flow rate of the O₂ gas is adjusted by the MFC 241 d,and the O₂ is supplied into the process chamber 201 via the gas supplypipe 232 b and the nozzle 249 b and is exhausted through the exhaustport 231 a. In this operation, the O₂ gas is supplied to the wafer 200.At this time, the valves 243 g and 243 h may be opened to allow a N₂ gasto be supplied into the process chamber 201 via the nozzles 249 a and249 b.

The process conditions of this step are exemplified as follows.

-   -   O₂ gas supply flow rate: 0.1 to 10 slm    -   O₂ gas supply time: 1 to 120 seconds, specifically 1 to 60        seconds    -   Processing pressure: 1 to 4,000 Pa, specifically 1 to 3,000 Pa    -   Other process conditions are the same as the process conditions        in step D1.

By supplying the O₂ gas to the wafer 200 under the aforementionedconditions, at least a portion of the layer containing Si and C formedon the SiN film on the wafer 200 is oxidized (modified). By modifyingthe layer containing Si and C, a silicon oxycarbide layer (SiOC layer)is formed as a layer containing Si, O, and C on the wafer 200, that is,on the SiN film on the wafer 200. When the SiOC layer is formed,impurities such as Cl contained in the layer containing Si and Cconstitute a gaseous substance containing at least Cl in the process ofmodifying the layer containing Si and C with the O₂ gas and aredischarged from the interior of the process chamber 201. As a result,the SiOC layer becomes a layer having fewer impurities such as Cl thanthe Si-containing layer formed in step D1 and the layer containing Siand C formed in step D2.

After the SiOC layer is formed, the valve 243 d is closed to stop thesupply of the O₂ gas into the process chamber 201. Then, a gas and thelike remaining in the process chamber 201 are removed from the processchamber 201 according to the same processing procedure as in the purgein step C1 (purge).

As a reaction gas (O-containing gas), in addition to the O₂ gas, it maybe possible to use, e.g., an ozone (O₃) gas, water vapor (H₂O gas), anitric oxide (NO) gas, or a nitrous oxide (N₂O) gas.

Step D4

After step D3 is completed, an NH₃ gas is supplied to the wafer 200 inthe process chamber 201 according to the same processing procedure asthe processing procedure in the above-described step C2 (NH₃ gassupply).

The process conditions of this step are exemplified as follows.

-   -   NH₃ gas supply flow rate: 0.1 to 10 slm    -   NH₃ gas supply time: 1 to 120 seconds, specifically 1 to 60        seconds    -   Processing pressure: 1 to 4,000 Pa, specifically 1 to 3,000 Pa    -   Other process conditions are the same as the process conditions        in step D1.

By supplying the NH₃ gas to the wafer 200 under the aforementionedconditions, at least a portion of the SiOC layer formed on the SiN filmon the wafer 200 is nitrided (modified). By modifying the SiOC layer, asilicon oxycarbonitride layer (SiOCN layer) is formed as a layercontaining Si, O, C, and N on the wafer 200, that is, on the SiN film onthe wafer 200. When the SiOCN layer is formed, impurities such as Clcontained in the SiOC layer constitute a gaseous substance containing atleast Cl in the process of modifying the SiOC layer with the NH₃ gas andare discharged from the interior of the process chamber 201. As aresult, the SiOCN layer becomes a layer having fewer impurities such asCl than the SiOC layer formed in step D3.

After the SiOCN layer is formed, the supply of the NH₃ gas into theprocess chamber 201 is stopped, and a gas and the like remaining in theprocess chamber 201 are removed from the interior of the process chamber201 according to the same processing procedure as in the purge in stepC1 (purge).

Performing Predetermined Number of Times

By performing a cycle a predetermined number of times (n times, where nis an integer of 1 or more), the cycle including non-simultaneously,that is, without synchronization, performing the above-described stepsD1 to D4, it is possible to form a SiOCN film having a predeterminedcomposition and a predetermined film thickness on the wafer 200, thatis, on the SiN film formed on the wafer 200 by performing the first filmformation.

In the second film formation, in the process of forming the SiOCN film,it is possible to supply a portion of the O component supplied to thewafer 200 or a portion of the O component contained in the SiOCN layerformed on the wafer 200 to the SiN film which is the base of the secondfilm formation. Accordingly, since the O component can be diffused andadded into the SiN film that is the base of the second film formation,it is possible to modify (oxidize) this SiN film into a SiON film havinga lower dielectric constant than the SiN film. As a result, as shown inFIG. 7D, it is possible to form a laminated film in which the SiON filmand the SiOCN film having low dielectric constants are laminated in thisorder, on the wafer 200, that is, on the W film exposed on the wafer200. This laminated film becomes a so-called low dielectric constantfilm (low-k film).

When the second film formation is performed, the O component that maydiffuse below the SiN film, that is, to the W film side that is the basewhen forming the laminated film, is trapped by the SiN film, that is, asthe SiN film itself is oxidized, so that its diffusion to the W filmside is blocked. By limiting the diffusion of the O component into the Wfilm by the SiN film in this way, it is possible to suppressre-oxidation of the W film from which the WO layer has been removed bythe temperature rise of the wafer 200 under the H₂ gas atmosphere. Inthe present disclosure, the effect of blocking the diffusion of the Ocomponent into the W film, which is obtained by the SiN film, that is,the effect of suppressing the oxidation of the W film, is also referredto as an oxidation-blocking effect.

The thickness of the SiOCN film formed in the second film formation maybe thicker than the thickness of the SiN film formed in the first filmformation. That is, the thickness of the SiN film formed in the firstfilm formation may be thinner than the thickness of the SiOCN filmformed in the second film formation. By doing so, when the second filmformation is performed, it is possible to oxidize the entire SiN filmformed in the first film formation to be modified into the SiON film,which makes it possible to modify the entire SiN film formed in thefirst film formation into a low dielectric constant film. As a result,it is possible to reduce the total dielectric constant of the laminatedfilm in which the first film and the second film are laminated. Further,by making the thickness of the SiOCN film having a lower dielectricconstant than the SiON film thicker than the thickness of the SiON film,that is, by making the thickness of the SiON film having a higherdielectric constant than the SiOCN film thinner than the thickness ofthe SiOCN film, it is possible to reduce the average dielectric constantof the laminated film in which the SiOCN film and the SiON film arelaminated.

The above-mentioned cycle may be repeated multiple times. That is, thethickness of the SiOCN layer formed when the above-mentioned cycle isperformed once may be set to be smaller than a desired film thickness,and the above-mentioned cycle may be repeated multiple times until thefilm thickness of a SiOCN film formed by laminating SiOCN layers reachesthe desired film thickness.

After-Purging and Returning to Atmospheric Pressure

After the formation of the SiOCN film as the second film and themodification of the SiN film formed as the first film into the SiON filmare completed, a N₂ gas as a purge gas is supplied from each of thenozzles 249 a and 249 b into the process chamber 201 and is exhaustedthrough the exhaust port 231 a. Thus, the interior of the processchamber 201 is purged to remove a gas, reaction by-products, and thelike remaining in the process chamber 201 from the interior the processchamber 201 (after-purge). After that, the internal atmosphere of theprocess chamber 201 is substituted with an inert gas (inert gassubstitution) and the internal pressure of the process chamber 201 isreturned to an atmospheric pressure (returning to atmospheric pressure).

Boat Unloading and Wafer Discharging

The seal cap 219 is moved down by the boat elevator 115 to open thelower end of the manifold 209. In addition, the processed wafers 200supported by the boat 217 are unloaded from the lower end of themanifold 209 to the outside of the reaction tube 203 (boat unloading).After the boat is unloaded, the shutter 219 s is moved and the lower endopening of the manifold 209 is sealed by the shutter 219 s via theO-ring 220 c (shutter close). The processed wafers 200 are unloaded outof the reaction tube 203 and are then discharged from the boat 217(wafer discharging).

(3) Effects According to the Present Embodiments

According to the present embodiments, one or more effects set forthbelow may be achieved.

(a) By performing the boat loading under the first temperature, it ispossible to suppress the oxidation of the W film exposed on the surfaceof the wafer 200. This makes it possible to suppress formation of afurther WO layer on the surface of the W film, increase in the thicknessof the already-formed WO layer, etc.

(b) By performing the ramp-up+H₂ pre-flow while raising the temperatureof the wafer 200 to the second temperature higher than the firsttemperature, it is possible to remove the WO layer formed on the surfaceof the W film. It is also possible to prevent re-oxidation of thesurface of the W film after removing the WO layer.

(c) By performing the first film formation before the second filmformation, when the second film formation is performed, it is possibleto block the O component that may diffuse below the SiN film, that is,the O component that may reach the W film. The diffusion-blocking actionof the O component by this SiN film makes it possible to prevent there-oxidation of the W film from which the WO layer has been removed bythe ramp-up+H₂ pre-flow.

(d) In the second film formation, by using the second process gasincluding an oxidizing gas, it is possible to form the SiOCN film havinga low dielectric constant on the wafer 200.

(e) By performing the second film formation, it is possible to oxidizethe SiN film formed in the first film formation to form the SiON film.As a result, it is possible to make the laminated film, which is formedby laminating the first film and the second film, into a low dielectricconstant film.

(f) By making the thickness of the SiOCN film formed in the second filmformation thicker than the thickness of the SiN film formed in the firstfilm formation, that is, by making the thickness of the SiN layer formedin the first film formation thinner than the thickness of the SiOCN filmformed in the second film formation, the oxidation of the SiN film canbe promoted, which makes it possible to further lower the dielectricconstant of the laminated film formed by laminating the first film andthe second film. Further, by increasing the ratio of the thicknessoccupied by the second film having a particularly low dielectricconstant to the total film thickness of the laminated film, that is, bydecreasing the ratio of the thickness occupied by the first film havinga higher dielectric constant than the second film to the total filmthickness of the laminated film, it is possible to further lower theaverage dielectric constant of the laminated film.

(g) As described above, according to the present embodiments, while anoxide film (the laminated film of the first film and the second film)formed on the W film is a low dielectric constant film, it is possibleto suppress the oxidation of the W film which is the base of the oxidefilm. The laminated film formed by the method of the present embodimentscan be suitably applied to, for example, a sidewall spacer, a hard mask,an etch stopper, and the like in a logic device such as a MPU, or amemory device such as a DRAM or a 3D NAND.

(h) By setting the second temperature and the third temperature to thesame temperature, it is not required to provide a step(temperature-rising step or temperature-falling step) of changing thetemperature of the wafer 200 between the first film formation and thesecond film formation, which makes it possible to improve the throughputof substrate processing.

(i) The effects of the present embodiments can be similarly obtainedeven when a precursor gas other than the HCDS gas is used, when aC-containing gas other than the C₃H₆ gas is used, when an O-containinggas other than the O₂ gas is used, when a N- and H-containing gas otherthan the NH₃ gas is used, when a reducing gas other than the H₂ gas isused, and when an inert gas other than the N₂ gas is used.

Other Embodiments

The embodiments of the present disclosure have been specificallydescribed above. However, the present disclosure is not limited to theabove-described embodiments, and various changes can be made withoutdeparting from the gist of the present disclosure.

In the above-described embodiments, the W film, which is an elementalmetal film, is exemplified as a conductive metal-containing film exposedon the surface of the substrate, but the present disclosure is notlimited to such embodiments. For example, the conductivemetal-containing film exposed on the surface of the substrate may be ametal nitride film such as a titanium nitride film (TiN film) or atungsten nitride film (WN film), or an elemental metal film such as analuminum film (Al film), a cobalt film (Co film), a nickel film (Nifilm), a platinum film (Pt film), or a copper film (Cu film). Even inthese cases, the same effects as those in the above-describedembodiments can be obtained. In the present disclosure, the conductivemetal-containing film such as the TiN film or the W film is also simplyreferred to as a metal film.

In the first film formation, as the first process gas (precursor gas),in addition to the above-mentioned various halosilane-based gases suchas the HCDS gas, it may be possible to use, e.g., analkylhalosilane-based gas such as a1,1,2,2-tetrachloro-1,2-dimethyldisilane ((CH₃)₂Si₂Cl₄, abbreviation:TCDMDS) gas, an alkylsilane-based gas such as a hexamethyldisilane((CH₃)₃—Si—Si—(CH₃)₃, abbreviation: HMDS) gas, or analkylenesilane-based gas such as a 1,4-disilabutane (Si₂C₂H₁₀,abbreviation: DSB) gas. For example, as a gas that promotesdecomposition of the precursor gas, a H₂ gas, a trichloroborane (BCl₃)gas, or the like may be added to the precursor gas. Further, as thefirst process gas (reaction gas), in addition to the above-mentionedvarious reaction gases, it may be possible to use an amine-based gassuch as a triethylamine ((C₂H₅)₃N, abbreviation: TEA) gas. Then,according to the gas-supplying sequences shown below, a SiN film, asilicon carbide film (SiC film), or a silicon carbonitride film (SiCNfilm) may be formed as the first film on the wafer 200, that is, on ametal-element-containing film exposed on the surface of the wafer 200and from which a native oxide film has been removed by a reductionprocess. Even in this case, the same effects as those in theabove-described embodiments can be obtained. The alkylhalosilane-basedgas, the alkylsilane-based gas, and the alkylenesilane-based gas aregases that act as a Si source and a C source, and the amine-base gas isa gas that acts as a N source and a C source.

(DCS→NH₃)×m⇒SiN

(HCDS→C₃H₆=NH₃)×m⇒SiCN

(HCDS→TEA)×m⇒SiCN

(TCDMDS→NH₃)×m⇒SiCN

(DSB+H₂)×m⇒SiC

(DSB+BCl₃)×m⇒SiC

When the SiC film or the SiCN film is formed as the first film in thefirst film formation, the SiC film or the SiCN film formed in the firstfilm formation is oxidized by performing the second film formation, soas to be modified into a SiOC film or a SiOCN film, respectively. Inthis case, since the SiOC film and the SiOCN film have a lowerdielectric constant than the SiON film, it is possible to further lowerthe dielectric constant of the laminated film formed by laminating thefirst film and the second film.

In the second film formation, as the second process gas (precursor gas),in addition to the above-mentioned various halosilane-based gases suchas the HCDS gas, it may be possible to use an alkylhalosilane-based gassuch as a TCDMDS gas, an alkylsilane-based gas such as a HMDS gas, analkylenesilane-based gas such as a DSB gas. Further, as the secondprocess gas (reaction gas), in addition to the above-mentioned variousreaction gases, it may be possible to use an amine-based gas such as aTEA gas. Then, according to the gas-supplying sequences shown below, aSiOCN film may be formed as the second film on the wafer 200, that is,on the first film. Further, the type of the second process gas may beappropriately selected to form a silicon oxide film (SiO film), asilicon oxynitride film (SiON film), and a silicon oxycarbide film (SiOCfilm) as the second film. Even in this case, the same effects as thosein the above-described embodiments can be obtained.

(HCDS→C₃H₆=NH₃=O₂)×n⇒SiOCN

(HCDS→TEA=O₂)×n⇒SiOCN

(TCDMDS→NH₃→O₂)×n⇒SiOCN

Recipes used in each process may be prepared individually according tothe processing contents and may be stored in the memory 121 c via atelecommunication line or the external memory 123. Moreover, at thebeginning of each process, the CPU 121 a may properly select anappropriate recipe from the recipes stored in the memory 121 c accordingto the processing contents. Thus, it is possible for a single substrateprocessing apparatus to form films of various kinds, composition ratios,qualities, and thicknesses with enhanced reproducibility. Further, it ispossible to reduce an operator's burden and to quickly start eachprocess while avoiding an operation error.

The recipes mentioned above are not limited to newly-prepared ones butmay be prepared, for example, by modifying existing recipes that arealready installed in the substrate processing apparatus. Once therecipes are modified, the modified recipes may be installed in thesubstrate processing apparatus via a telecommunication line or arecording medium storing the recipes. In addition, the existing recipesalready installed in the substrate processing apparatus may be directlymodified by operating the input/output device 122 of the substrateprocessing apparatus.

The example in which a film is formed by using a batch-type substrateprocessing apparatus capable of processing a plurality of substrates ata time has been described in the above-described embodiments. Thepresent disclosure is not limited to the above-described embodiments,but may be suitably applied, for example, to a case where a film isformed by using a single-wafer-type substrate processing apparatuscapable of processing a single substrate or several substrates at atime. In addition, the example in which a film is formed by using asubstrate processing apparatus including a hot-wall-type process furnacehas been described in the above-described embodiments. The presentdisclosure is not limited to the above-described embodiments, but may besuitably applied to a case where a film is formed by using a substrateprocessing apparatus including a cold-wall-type process furnace.

Even in the case of using these substrate processing apparatuses, eachprocess may be performed according to the same processing procedures andprocess conditions as those in the above-described embodiments, and thesame effects as those in the above-described embodiments can beachieved.

The above-described embodiments may be used in proper combination. Theprocessing procedures and process conditions used in this case may bethe same as, for example, the processing procedures and processconditions of the above-described embodiments.

EXAMPLES

As Samples 1 to 5, the above-described substrate processing apparatuswas used to form a SiOCN film on a wafer in which a W film was exposedon the surface of the wafer according to the gas-supplying sequenceshown in FIG. 6. Before performing wafer charging and boat loading, thecomposition in the thickness direction of the W film in the initialstate in the wafer of Samples 1 to 5 was measured by XPS, respectively.As a result of the measurement, the ratio (%) of the thickness of a Wlayer, which is an unoxidized portion of the W film, and the thicknessof a WO layer, which is an oxidized portion of the W film, was 70:30.

When preparing Sample 1, the boat loading and the ramp-up+H₂ pre-flowunder the first temperature were performed in this order, and then,without performing the first film formation, the second film formationwas performed to directly form a SiOCN film on the W film withoutforming a SiN film on the W film. When preparing Samples 2 to 5, theboat loading and the ramp-up+H₂ pre-flow under the first temperaturewere performed in this order, and then, the first film formation and thesecond film formation were performed in this order to form a SiN filmand a SiOCN film on the W film in this order. That is, Samples 2 to 5were prepared according to the substrate-processing sequence shown inFIG. 4. The process conditions in each step when preparing each samplewere set to predetermined conditions within the process condition rangedescribed in the above-described embodiments. The process conditions forperforming the second film formation were the same conditions for eachsample. The thickness of the SiN film and the SiOCN film in each samplewas the thickness shown in FIG. 8, respectively.

After preparing Samples 1 to 5, the composition of the W film in Samples1 to 5 was measured by XPS, respectively. The result is shown in FIG. 8.As shown in FIG. 8, in Samples 2 to 5 in which the SiN film was formedbefore the SiOCN film was formed, the existence of the WO layer in the Wfilm could not be confirmed. It is considered that this is because theWO film formed on the surface of the W film in the initial state wasremoved by the ramp-up+H₂ pre-flow and the re-oxidation of the W filmwhen forming the SiOCN film could be avoided by the SiN film. On theother hand, in Sample 1 in which the SiN film was not formed before theSiOCN film was formed, the existence of the WO layer in the W film wasconfirmed. It is considered that this is because the WO film formed onthe surface of the W film in the initial state was removed by theramp-up+H₂ pre-flow, but a portion of the W film was re-oxidized whenthe SiOCN film was formed.

According to the present disclosure, it is possible to provide atechnique capable of suppressing the oxidation of a film formed on asubstrate when the base of the film is a metal-element-containing film,while the film is a low dielectric constant film.

What is claimed is:
 1. A method of manufacturing a semiconductor device,comprising: (a) loading a substrate where a conductivemetal-element-containing film is exposed on a surface of the substrateinto a process chamber under a first temperature; (b) supplying areducing gas to the substrate while raising a temperature of thesubstrate to a second temperature higher than the first temperature inthe process chamber; (c) forming a first film, which contains siliconand at least one selected from the group of nitrogen and carbon and doesnot contain oxygen, on the metal-element-containing film, by supplying afirst process gas, which does not include an oxidizing gas, to thesubstrate under the second temperature in the process chamber; and (d)forming a second film, which contains silicon, oxygen, carbon, andnitrogen, on the first film such that the second film is thicker thanthe first film, by supplying a second process gas, which includes anoxidizing gas, to the substrate under a third temperature higher thanthe first temperature in the process chamber.
 2. The method of claim 1,wherein the first temperature is set to a room temperature or higher and200 degrees C. or lower.
 3. The method of claim 1, wherein the firsttemperature is set to a room temperature or higher and 150 degrees C. orlower.
 4. The method of claim 1, wherein at least one selected from thegroup of a hydrogen gas and a deuterium gas is used as the reducing gas.5. The method of claim 1, wherein in (b), a native oxide film formed ona surface of the metal-element-containing film is removed by thetemperature rise under a reducing gas atmosphere.
 6. The method of claim5, wherein in (b), an oxidation of the surface of themetal-element-containing film where the native oxide film has beenremoved is prevented.
 7. The method of claim 6, wherein the secondtemperature is set to 500 degrees C. or higher and 800 degrees C. orlower.
 8. The method of claim 6, wherein the second temperature is setto 600 degrees C. or higher and 700 degrees C. or lower.
 9. The methodof claim 1, wherein the first film includes at least one selected fromthe group of a silicon nitride film, a silicon carbide film, and asilicon carbonitride film.
 10. The method of claim 1, wherein athickness of the first film is 0.16 nm or more and 1 nm or less.
 11. Themethod of claim 1, wherein a thickness of the first film is 0.16 nm ormore and 0.48 nm or less.
 12. The method of claim 1, wherein a thicknessof the first film is 0.16 nm or more and 0.32 nm or less.
 13. The methodof claim 1, wherein the first process gas includes: a gas serving as asilicon source or a gas serving as a silicon source and a carbon source;and a gas serving as at least one selected from the group of a nitrogensource and a carbon source, and wherein in (c), a cycle which includessupplying the respective gases of the first process gas is performed oneto three times.
 14. The method of claim 1, wherein the first process gasincludes: a gas serving as a silicon source or a gas serving as asilicon source and a carbon source; and a gas serving as at least oneselected from the group of a nitrogen source and a carbon source,wherein in (c), the respective gases of the first process gas areintermittently supplied to the substrate, wherein the second process gasincludes: a gas serving as a silicon source or a gas serving as asilicon source and a carbon source; a gas serving as at least oneselected from the group of a nitrogen source and a carbon source; and agas serving as an oxygen source, and wherein in (d), the respectivegases of the second process gas are intermittently andnon-simultaneously supplied to the substrate.
 15. The method of claim 1,wherein in (d), the first film formed in (c) is modified into a filmhaving a dielectric constant lower than a dielectric constant of thefirst film before performing (d).
 16. The method of claim 1, wherein in(c), a silicon carbonitride film is formed as the first film, andwherein in (d), a silicon oxycarbonitride film is formed as the secondfilm, and the first film is modified from the silicon carbonitride filminto a silicon oxycarbonitride film.
 17. The method of claim 16, whereinthe first process gas includes: a gas serving as a silicon source; a gasserving as a carbon source; and a gas serving as a nitrogen source,wherein in (c), the respective gases of the first process gas areintermittently supplied to the substrate, and wherein the second processgas includes: a gas serving as a silicon source; a gas serving as acarbon source; a gas serving as a nitrogen source; and a gas serving asan oxygen source, and wherein in (d), the respective gases of the secondprocess gas are intermittently and non-simultaneously supplied to thesubstrate.
 18. The method of claim 1, wherein the second temperature andthe third temperature are set to be the same temperature.
 19. A methodof processing a substrate, comprising: (a) loading the substrate where aconductive metal-element-containing film is exposed on a surface of thesubstrate into a process chamber under a first temperature; (b)supplying a reducing gas to the substrate while raising a temperature ofthe substrate to a second temperature higher than the first temperaturein the process chamber; (c) forming a first film, which contains siliconand at least one selected from the group of nitrogen and carbon and doesnot contain oxygen, on the metal-element-containing film, by supplying afirst process gas, which does not include an oxidizing gas, to thesubstrate under the second temperature in the process chamber; and (d)forming a second film, which contains silicon, oxygen, carbon, andnitrogen, on the first film such that the second film is thicker thanthe first film, by supplying a second process gas, which includes anoxidizing gas, to the substrate under a third temperature higher thanthe first temperature in the process chamber.
 20. A substrate processingapparatus comprising: a process chamber in which a substrate isprocessed; a heater configured to heat the substrate in the processchamber; a reducing gas supply system configured to supply a reducinggas to the substrate in the process chamber; a first process gas supplysystem configured to supply a first process gas, which does not includean oxidizing gas, to the substrate in the process chamber; a secondprocess gas supply system configured to supply a second process gas,which includes an oxidizing gas, to the substrate in the processchamber; a transfer system configured to transfer the substrate into theprocess chamber; and a controller configured to be capable ofcontrolling the heater, the reducing gas supply system, the firstprocess gas supply system, the second process gas supply system, and thetransfer system so as to perform a process including: (a) loading thesubstrate where a conductive metal-element-containing film is exposed ona surface of the substrate into the process chamber under a firsttemperature; (b) supplying the reducing gas to the substrate whileraising a temperature of the substrate to a second temperature higherthan the first temperature in the process chamber; (c) forming a firstfilm, which contains silicon and at least one selected from the group ofnitrogen and carbon and does not contain oxygen, on themetal-element-containing film, by supplying the first process gas to thesubstrate under the second temperature in the process chamber; and (d)forming a second film, which contains silicon, oxygen, carbon, andnitrogen, on the first film such that the second film is thicker thanthe first film, by supplying the second process gas to the substrateunder a third temperature higher than the first temperature in theprocess chamber.
 21. A non-transitory computer-readable recording mediumstoring a program that causes, by a computer, a substrate processingapparatus to perform a process comprising: (a) loading a substrate wherea conductive metal-element-containing film is exposed on a surface ofthe substrate into a process chamber of the substrate processingapparatus under a first temperature; (b) supplying a reducing gas to thesubstrate while raising a temperature of the substrate to a secondtemperature higher than the first temperature in the process chamber;(c) forming a first film, which contains silicon and at least oneselected from the group of nitrogen and carbon and does not containoxygen, on the metal-element-containing film, by supplying a firstprocess gas, which does not include an oxidizing gas, to the substrateunder the second temperature in the process chamber; and (d) forming asecond film, which contains silicon, oxygen, carbon, and nitrogen, onthe first film such that the second film is thicker than the first film,by supplying a second process gas, which includes an oxidizing gas, tothe substrate under a third temperature higher than the firsttemperature in the process chamber.